This invention relates generally to visual surveillance and, more particularly, to a method and system for projective camera calibration.
In the context of visual surveillance of human activity, for example, knowledge about a camera's internal and external parameters is useful, as it allows for the establishment of a connection between image and world measurements. Unfortunately, calibration information is rarely available and difficult to obtain after a surveillance system has been installed.
The connection between image measurements and scene measurements in metric space is greatly simplified when intrinsic and extrinsic parameters of the camera are available. The two general approaches to establish these parameters are known as camera calibration, wherein extensive knowledge of the scene geometry must be available, and camera autocalibration, wherein knowledge of the camera motion and rigidity of a scene, rather than knowledge of the scene geometry, is required.
Conventional surveillance systems have dealt with small amounts of measurement noise and outliers using an estimation that, in practice, quickly breaks down when the noise reaches significant levels.